The present invention relates to a method for the production of dihydroxybenzophenones, and more particularly, it relates to a method for electrocatalytically oxidizing bis(4-hydroxyphenyl)methanes, or the quinone methide intermediate, with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) to produce 4,4'-dihydroxybenzophenones.
Certain benzophenone derivatives are commercially important as light stabilizing additives for various synthetic plastics. See, for example, Goldberg U.S. Pat. No. 3,291,837 wherein 2-hydroxy-3-halopropyl benzophenone ether stabilizing agents are prepared by the catalyzed reaction of a benzophenone intermediate with an epihalohydrin.
Other forms of benzophenones, particularly bisphenol K (4,4'-dihydroxybenzophenone) and substituted bisphenol K, are useful as monomers in the production of synthetic resins. For example, epoxy resins, which are useful as coatings, adhesives and casting resins, can be prepared from the reaction of a bisphenol and epichlorohydrin. Likewise, polycarbonate resins, which are useful as coatings and casting resins, can be prepared from the reaction of a bisphenol and phosgene.
Accordingly, the need exists for a process by which large quantities of dihydroxybenzophenones can be produced economically and at high yields.